The Nielsen .50 235 grain slugs are equipped with a large hollow point and dish base.
These slugs are great for precision shooting with .50 PCP air rifles.
 
Because the Nielsen slugs are not cast, but are cold swaged with softer lead, they expand much faster on impact.
An additional advantage is that the slug quickly forms to the features and fields of the barrel and therefore seals better.
 
Nielsen Specialty Ammo (NSA) is characterized by the extreme uniformity that the manufacturing process entails.  The weight of the slugs are extremely close together and they are also perfectly round, achieving an exact weight distribution.  This guarantees extreme precision.